fxrates

fxrates reads foreign-exchange data from the Frankfurter API: which currencies are supported, what the latest rates are, what the rates were on a single past date or across a range, and conversions between currencies worked out locally from the fetched rate. One binary serves a command-line interface and a stdio MCP server.

No API key is needed. The service is keyless, so fxrates works with nothing configured. The API base URL can be overridden with FRANKFURTER_API_URL; when it is not set, calls go to https://api.frankfurter.dev/v1.

Install

npx @reneturcios/fxrates currencies

Or run the container image:

docker run -i ghcr.io/cloudcorprecords/fxrates

The container defaults to the MCP server (see below). Pass CLI arguments to use it as a CLI instead.

Related MCP server: FX Currency MCP Server

CLI

fxrates currencies
fxrates latest --base USD --symbols EUR,GBP
fxrates convert 25 EUR USD
fxrates historical 2024-05-01 --base EUR --symbols USD
fxrates range 2024-05-01 2024-05-03 --base EUR
fxrates convert-on 2020-01-02 100 USD EUR
fxrates greet Ada

fxrates --version

Rate commands print the upstream JSON payload. Conversions print a JSON object with amount, from, to, rate, converted, and date when the API supplies one. Exit codes: 0 on success, 1 when a call fails (including an upstream API error), 2 for usage errors.

Conversions are computed locally: the tool fetches the single rate it needs and multiplies. The result is trimmed to at most six decimal places by rounding at the sixth place; no fee, spread, or extra rounding is applied.

MCP server

One bin serves both faces. The mcp subcommand starts a stdio MCP server:

npx -y @reneturcios/fxrates mcp

MCP client configuration:

{
  "mcpServers": {
    "fxrates": {
      "command": "npx",
      "args": ["-y", "@reneturcios/fxrates", "mcp"]
    }
  }
}

To point the server at a different Frankfurter-compatible host, add FRANKFURTER_API_URL to the client's env for this server.

Tools

Dates use YYYY-MM-DD. symbols is a comma-separated list such as USD,GBP. Currency arguments are codes such as EUR and USD.

Development

npm install
npm run build   # tsc -> dist/
npm test        # node test runner over test/*.test.ts, no network (fake fetch fixtures)
npm run dev     # run the CLI from source via tsx

License

MIT — see LICENSE.